What is an elder? Here is the role of an elder as explained in in the PCA book of church order.
The Elder 8-1. This office is one of dignity and usefulness. The man who fills it has in Scripture different titles expressive of his various duties. As he has the oversight of the flock of Christ, he is termed bishop or pastor. As it is his duty to be grave and prudent, an example to the flock, and to govern well in the house and Kingdom of Christ, he is termed presbyter or elder. As he expounds the Word, and by sound doctrine both exhorts and convinces the gainsayer, he is termed teacher. These titles do not indicate different grades of office, but all describe one and the same office.
8-2. He that fills this office should possess a competency of human learning and be blameless in life, sound in the faith and apt to teach. He should exhibit a sobriety and holiness of life becoming the Gospel. He should rule his own house well and should have a good report of them that are outside the Church.
8-3. It belongs to those in the office of elder, both severally and jointly, to watch diligently over the flock committed to his charge, that no corruption of doctrine or of morals enter therein. They must exercise government and discipline, and take oversight not only of the spiritual interests of the particular church, but also the Church generally when called thereunto. They should visit the people at their homes, especially the sick. They should instruct the ignorant, comfort the mourner, nourish and guard the children of the Church. They should set a worthy example to the flock entrusted to their care by their zeal to evangelize the unconverted and make disciples. All those duties which private Christians are bound to discharge by the law of love are especially incumbent upon them by divine vocation, and are to be discharged as official duties. They should pray with and for the people, being careful and diligent in seeking the fruit of the preached Word among the flock.
8-4. As the Lord has given different gifts to men and has committed to some special gifts and callings, the Church is authorized to call and appoint some to labor as teaching elders in such works as may be needful to the Church. When a teaching elder is called to such needful work, it shall be incumbent upon him to make full proof of his ministry by disseminating the Gospel for the edification of the Church. He shall make a report to the Presbytery at least once each year.
8-5. When a man is called to labor as a teaching elder, it belongs to his order, in addition to those functions he shares with all other elders, to feed the flock by reading, expounding and preaching the Word of God and to administer the Sacraments. As he is sent to declare the will of God to sinners, and to beseech them to be reconciled to God through Christ, he is termed ambassador. As he bears glad tidings of salvation to the ignorant and perishing, he is termed evangelist. As he stands to proclaim the Gospel, he is termed preacher. As he dispenses the manifold grace of God, and the ordinances instituted by Christ, he is termed steward of the mysteries of God.
8-6.When a teaching elder is appointed to the work of an evangelist in foreign countries or where there are no other PCA churches within a reasonable distance, he is commissioned for a renewable term of twelve months to preach the Word, to administer the Sacraments, to receive and dismiss members of mission churches, and to train potential officers. By separate actions the Presbytery may in extraordinary situations commission him to examine, ordain and install ruling elders and deacons and organize churches.
8-7. A Presbytery may, at its discretion, approve the call of a teaching elder to work with an organization outside the jurisdiction of the Presbyterian Church in America, provided that he be engaged in preaching and teaching the Word, that the Presbytery be assured he will have full freedom to maintain and teach the doctrine of our Church, and that he report at least annually on his work. As far as possible, such a teaching elder shall be a member of the Presbytery within whose bounds he labors. (See BCO 20-1.)
8-8. As there were in the Church under the law, elders of the people for the government thereof, so in the Gospel Church, Christ has furnished others besides ministers of the Word with gifts and commission to govern when called thereunto, who are called ruling elders.
8-9. Elders being of one class of office, ruling elders possess the same authority and eligibility to office in the courts of the Church as teaching elders. They should, moreover, cultivate zealously their own aptness to teach the Bible and should improve every opportunity of doing so.