yes, it's stands for it is so. It's Sentences (Meaning "It Is") It's a very cold day today. It's a good idea to begin studying for your calculus exam, noted Professor James.It's a beautiful day.
By the way, did you leave your wet umbrella by the door?Stop in to say hello the next time you pass by.The Post Office is by the library, they're both on your left.By the way, you're a poor speller.