In context, for the Holy Spirit to be upon Simeon means that he was specially prepared to meet the Messiah. The Spirit revealed to him that he would meet the Messiah before his death, and the Spirit also providentially prompted Simeon to visit the temple on the same day that Jesus was there with his parents.
25 Now there was a man in Jerusalem, whose name was Simeon, and this man was righteous and devout, waiting for the consolation of Israel, and the Holy Spirit was upon him.