Child tax credit?

I thought the additional child tax credit we are getting in July was just extra tax credit. But I watched this video of someone explaining it and now Im confused. We have 2 kids under 5 so we are estimating we will get about $600($300 each) in July and so forth. Eventually equally to a total of $1,600 per child since we already got $2,000 per child in our income taxes this year. All together that equals $3,600 in child tax credits for the year.

The video I watched made it sound like the additional $1,600 per child, would come out of our child tax credit next year for 2021. Basically, the money is an advance of next years income tax and not really “extra money”.

Anyone know or have information on it?