He put a barrier around the vineyard. It could have been a row of shrubs, a fence, or a stone wall.
# dug a pit for a winepress
This means that he carved a pit on the rock, which would be the bottom part of the winepress used for collecting the squeezed grape juice. AT: "carved a pit into rock for the winepress" or "he made a vat to collect the juice from the winepress" (See: [[rc://en/ta/man/translate/figs-explicit]])
The owner still owned the vineyard, but he allowed the vine growers to take care of it. When the grapes became ripe, they were to give some of them to the owner and keep the rest.
This refers to the time of harvest. This can be made clear. AT: "When the time came to harvest the grapes" (See: [[rc://en/ta/man/translate/figs-explicit]])