Love (Gr. agape) involves demonstrating genuine concern for the welfare of another person regardless of that one"s attractiveness or ability to return love (cf. Romans 12:14-21). The enemies in view would be people who oppose disciples because of their commitment to Jesus. To bless (Gr. eulogeite) here means to wish someone well contrasted with cursing or wishing someone evil. "Pray" (Gr. proseuchesthe, the general word for prayer) in this context means asking God to do them good when they do you evil. [source][source][source]