This can also be translated as "people see for themselves and know."
## the summer is near ##
"the summer is about to start." Summer in Israel is very dry, so crops are harvested at the beginning of summer. The meaning is "harvest time is ready to start." This is implied information that they would see and know. (See: [[rc://en/ta/man/translate/figs-explicit]])
## the kingdom of God is near ##
"the kingdom of God will soon be established" or "God will reign over his kingdom"