A sosta is a pause or break. In this context it means 'stopping'
Divieto di sosta = no stopping
Solo = only
Salita e discesa = Getting on and getting off
passeggeri = passengers
In other words, coaches can only stop to let passengers on and off.
The translation on the sign implies a great scooping up and offloading of people.
-------------------------------------------------------
Discesa is pronounced something like dee-shay-za (with the stress on shay). The combination of the letters sc gives a sh sound in Italian.
pesce (fish) pronounced pay-shay
biscia (snake) pronounced bee-sha

You might see this sign and wonder if dalle is a very important word. It isn't really but you might think it is. It just means 'from' as in da le ore (from the hours). When da is followed by le it combines to become dalle.  With la it becomes dalla. With il it becomes dal. With lo it becomes dallo. With i it becomes dai and with gli it becomes dagli. Confusing or what. But once you know about these options, signs become much easier to read.
And if you are wondering, you need to buy a ticket between 9am and 7pm.