That is an excellent question that many new believers ask. It is true that God already knows what will happen because he is not limited by time or space. The Bible contains numerous references to God’s foreknowledge, a term that means God knows the future. However, we humans do not know the future unless God reveals it to us. We do not know what may or may not happen from one day to the next, and it is this reality that makes prayer necessary. The Bible gives several reasons to pray. Below are just a few of those reasons:
To fellowship with God.
To obey God.
To relieve anxiety and worry.
To encourage other believers.
To see God work in specific ways (it makes us attentive to his workings)