what to grow inside your house on a window will?

Do you mean to start them off or to get to full size?

There is very little you can grow to full size on a window sill as it is not usually bright enough though of course you can sprout seeds for eating as sprouted seeds. If you have a large, fairly deep windowsill in a south or southwest facing window that gets lots of sunshine and is not going to be interfered with by curtains or blinds you could possibly grow bush tomatoes in a couple of months.

In the same situation there are quite a lot of plants you can start from seed, but don't start them too early as you have to be able to put them out when they are ready. If the window is not bright enough they will grow spindly and not be a lot of use. If you had even a cold frame outside to transfer them to after they have been pricked out that would be very helpful, again make sure it has plenty of light.

Root veg are mostly better sown where they are going to grow, but most herbs, brassicas (members of the cabbage/brocolli/kale family), peas and beans, onions and leeks, marrows can be started on a window sill. Check out individual packets to see exactly when to sow them. Cover the seed trays with a plastic cover or bag to stop them drying out.