Depending on what time of day you leave, and en-route connections it will be around 10 hours.
Distance between Monaco and Venice is 268 miles or 431.21 Kilometers
about 3 hours by train
On the high-speed day train the trip from Paris to Venice will take around 4 and a half hours while if you take the night train, it will be around 12 hours.
How long it takes to get from Venice to Brindisi on the train depends on the service. It can take between 8.5 and 9.5 hours to travel between the two cities.
San Mariano is in the Philippines (according to Wikipedia). There is no way you can get a train there from Venice!
heskey
If it's a non-stop bus, that's about a 5 hour trip.
The train journey from Florence to Venice takes approximately 2 hours and 30 minutes.
The fastest trains take 6h28 (with one change, at Villach).
By train, its about 3 hours.
About 7h10 (including changes en route).
To be honest, it's probably better to fly, but if you want to take the train, you will need to take a train first from Barcelona to Venice in Italy. Then you will need to take the train from Venice to Vienna.