The ninth hour (3:00 p.m.) was the Jewish hour of prayer (cf. Acts 3:1), so Cornelius may have been praying. Again God prepared two people to get together by giving each of them a vision (cf. Saul and Ananias). Cornelius saw an angel, not Jesus ( Acts 10:7; Acts 10:22; Acts 10:30; Acts 11:13; cf. Acts 1:20). "Lord" here is a respectful address such as " Sirach ," but the centurion undoubtedly felt great awe when he saw this supernatural visitor (cf. Acts 10:30). Cornelius was not calling the angel his Savior or his Sovereign. God had noted Cornelius" piety (his prayers Godward, proseuchai, and his alms manward, cf. Acts 10:2) and was now going to give him more revelation. [source][source][source]
"Luke is suggesting that the prayers and the alms of this Gentile were accepted by God in lieu of the sacrifices which he was not allowed to enter the Temple to offer himself. In other words, God had acted to break down barriers between Jew and Gentile by treating the prayers and alms of a Gentile as equivalent to the sacrifice of a Jew." [1][source]
Modern missionaries have told stories of similar seekers after God. After they penetrated some remote tribe and preached the gospel, the natives explained how they had previously worshiped the God the missionary preached and had prayed for more light. Romans 3:11 means that no one seeks God unless God draws him or her to Himself, which is what God did with Cornelius. [source][source][source]