A valise is a small suitcase. If you're carrying a valise as you climb onto a train, you're probably heading off on a short vacation or a weekend trip to visit a friend.
The noun valise sounds a little old-fashioned these days, but it's still a good way to talk about a satchel or overnight bag. You might pack a valise for a night at your sister's house, or carry a valise onto an airplane. In the 1600's, valise was often used to mean a soldier's small bag, and while the word has a Latin root, valisia, experts aren't sure what its origins might be.