I mean this kindly, I would return this PC and get your money back.
My son asked for a gaming pc and we spent a long time researching it, you can't get anything decent for that price. You will also need monitor, keyboard, mouse, head set etc.
What games does he want to play? As that will make a big difference.
My son got this one custom made, refurbished in the end (spec below) it was about £800 and he has since spent some more upgrading it as well. He used all of his birthday and Christmas money from all of his relatives to buy it.
Very minimum you want at least an i5 processor, 16gb RAM, 8gb graphics card. Bonus is solid state drive.
Specification:
Processor: Intel Quad i7 4770 3.4 GHz
Storage: New 240 GB Solid State Drive (system)
1 TB HDD (for additional Storage)
Memory Ram: 16 GB (have since upgraded this)
New Graphics Card - 8GB RTX 3050
Processor: Intel i7
RAM: 16GB
Graphics: Nvidia GeForce
SSD/HDD: SSD
Total Storage: 1001-2000GB