She'd is a contraction, which means it combines two words by squeezing them together and dropping some letters. Specifically, she'd stands for either “she had” or “she would,” depending on the sentence.

When you see she'd in a sentence like “She'd already finished her homework,” it means “she had.” When you see it in “She'd love to come to your party,” it means “she would.” The context makes it clear which meaning fits.

Contractions like she'd make speaking and writing feel more natural and conversational. Compare “She would have come if she had known” with “She'd have come if she'd known.” The second version flows more smoothly and sounds like how people actually talk.

Other similar contractions include he'd, they'd, and we'd. You'll find contractions everywhere in casual writing and dialogue in books, but in formal writing like research papers or business letters, writers usually spell out both words instead.