Learn Russian: Сколько это стоит?

They look very similar, but they are different verbs! стОит (costs) comes from стоить (to cost) and has the stress on the first syllable. The word for "it stands" is стоИт (from стоять) and has the stress on the last syllable.

Does сколько mean "how much" or "how many"?

It means both! In Russian, you use сколько for both countable things (how many) and uncountable things (how much). Here, combined with стоит (costs), it means "how much".

Why do we use это here instead of он or она?

We use это (this) when asking about the general price of an object in front of us, without worrying about its grammatical gender. If you were pointing at a masculine noun like a phone (телефон), you could technically ask "how much does it cost" using the masculine "he" (Сколько он стоит?), but Сколько это стоит? is the perfect universal way to ask.

Can I change the word order to Сколько стоит это?

Yes, you can. Russian word order is very flexible. However, Сколько это стоит? is the most common and natural way a native speaker will ask this question in a shop.