With this 300$ you can rent servers for up to 3 months.
For example you can spend it on renting a Linux server with 16 GB and 4 vCPU for 3 months.
This is much cheaper than regular hosting services offer
You can buy an account here: https://shoppy.gg/product/vhMcbIN
Right now there is a 5$ discount and the account costs 15$. The price will be increased later
If you have any questions - my discord is Belian#1213