E “who believes” = pisteuo. From pistis (faith, faithfulness, belief, trust, confidence; to be persuaded or come to trust); from peitho (to have confidence, urge, be persuaded, agree, assure, believe, have confidence, trust). This is to believe, entrust, have faith it, affirm, have confidence in. This is less to do with a series of beliefs or doctrines that one believes and more to do with faithfulness, loyalty, and fidelity. It is trusting and then acting based on that trust.
F “scripture” = graphe. From grapho (to write). This is literally writing, a document. In the New Testament, this is always used for scripture.
G “heart” = koilia. From koilos (hollow). This is belly or organs in the abdomen. So, it could be stomach, womb, or heart. Figuratively, this refers to one’s inner self.
H “rivers” = potamos. Related to “drink” in v37. 17x in NT. From pino (to drink). This is a river, brook, or water. It can also be a riverbed flowing with heavy rain or melted snow (like an arroyo).