It’s and its sound alike, but their meanings are quite different. It is not uncommon to confuse the two, but your English will confuse other people if you use the wrong one!
It’s is a contraction for it is (or it has). For example, “It’s a beautiful day today.” This is a very common contraction to hear in spoken English. This is the same contraction Dominique uses when she says, “It’s nice and cozy.” This has the same meaning as, “It is nice and cozy.”
Its is a possessive adjective. It modifies a noun by telling us to whom it belongs. For example, “The cat is washing its paw,” or, “The company hired its first worker.” Other possessive adjectives include my, your, his, her, our, and their.
The rule to remember is this: If you mean “It is” or “It has,” use it’s with an apostrophe (‘). If not, don’t use the apostrophe.