checkout
The place or process where you pay before leaving a store.
Checkout is the place in a store where you pay for items you want to buy. At the checkout, a cashier scans your purchases, tells you the total cost, and takes your payment. Grocery stores often have multiple checkout lanes where customers line up with their carts, while smaller shops might have just one checkout counter near the exit.
The word also means the process of leaving a place after staying there. When your family checks out of a hotel, you return your room keys, settle any remaining charges, and officially end your stay. Libraries use the term too: when you check out a book, you're borrowing it and promising to return it by a certain date.
In online shopping, checkout means the final steps where you confirm what you're buying and enter your payment information. You might add items to your cart, then proceed to checkout to complete your purchase.
The phrase check out (as two words) has another casual meaning: to look at something interesting. If your friend says, “Check out this cool rock I found,” they're asking you to look at it and see what makes it special.