This is another unique section of this longer ending to Mark. Jesus was reminding his followers of what would happen to them. They would have special powers. They would be able to pick up snakes in their hands (ὄφεις ἀροῦσιν). They would be able to drink any deadly drink (κἂν θανάσιμόν τι πίωσιν), without it hurting them (οὐ μὴ αὐτοὺς βλάψῃ). They would be able to lay their hands-on sick people (ἐπὶ ἀρρώστους χεῖρας ἐπιθήσουσιν) and they would recover or become well again (καὶ καλῶς ἕξουσιν). They would be like miracle workers or super heroes with special powers.
Matthew finished off this unique section by talking about the huge crowds that followed Jesus in Galilee (καὶ ἠκολούθησαν αὐτῷ ὄχλοι πολλοὶ ἀπὸ τῆς Γαλιλαίας). However, he added something that had not been talked about. Matthew said that the people from Decapolis (Δεκαπόλεως), Jerusalem (καὶ Ἱεροσολύμων), Judea (καὶ Ἰουδαίας), and from beyond on the east bank of the Jordan River (καὶ πέραν τοῦ Ἰορδάνου) were following Jesus. So far, Jesus has not done anything there. Decapolis was an area of 10 cities or towns east of Galilee, with 9 of these cities on the east side of the Jordan River that included Damascus. So that the news about Jesus may have spread there, as well on the east side of the Jordan. However, the mention of Jerusalem and Judea, which were way south, at least 100 miles away, seems like a stretch.