Borgolovo San Lorenzo is located in the heart of Venice not too far from San Marco Square. From the airport, the easiest option would be to take the Alilaguna Blue Line to the Ospedale Ferry Terminal. It's the third stop and about a 45-minute ride, but there will be no transfers. Another option would be to take the bus or a taxi from the airport to Piazzale Roma. This is the end of the line for land vehicles in Venice. From here it's on foot or by boat. From Piazzale Roma you have to take the Vaporetto, Line 1 or 2, and get off at the San Zaccaria Terminal. This option will take you straight down the Grand Canal, which could be a nice way to see Venice. Both of these options will require about a 10-minute walk from the ferry terminal to your accommodations. The Alilaguna option avoids a transfer from bus/taxi to boat and you will ride across the lagoon out to Venice, which can also provide a nice perspective.
To get to the train station when you leave you can hop on the Vaporetto at San Zaccaria and get off at the Ferrovia Terminal, which is directly in front of the train station. Both Vaporetto Lines 1 and 2 stop here.