She's is a contraction, which means it's two words squeezed together into one shorter word. The apostrophe shows where letters were removed to make the contraction.

She's combines she and is, as in “She's my best friend” (she is my best friend). It can also combine she and has, as in “She's been practicing piano for years” (she has been practicing).

You can figure out which meaning fits by looking at what comes next. If the next word describes something (tired, happy, the captain), you're probably reading “she is.” If you see words like been, done, or finished, you're reading “she has.”

Contractions like she's make speech and writing flow more naturally. “She is going to the library” sounds formal and stiff, while “She's going to the library” sounds like normal conversation. Writers use contractions in dialogue to make characters sound realistic, and people use them constantly when speaking.

Other common contractions work the same way: he's (he is/he has), it's (it is/it has), and that's (that is/that has). Don't confuse it's with its, though. The one with the apostrophe always means “it is” or “it has,” while its shows possession, like “the dog wagged its tail.”