Bios password

BIOS password on Dell laptops cannot be recovered. If you have forgotten one of the passwords that is set in the BIOS, contact Dell Technical Support to obtain a password release code. The password release code is based on the unique password prompt that is generated using information from your Dell laptop.

Be prepare to provide proof of ownership.

What do I use as proof of ownership

It can be vary, depending on the flexibility of Dell agents.  A reasonable process to protect locked devices for system owners.

@Chino de Oro

Would an email saying that I bought it by MasterCard be enough proof? 

You will need to verify the address and phone number on record with Dell when the system was either purchased or registered.

@ejn63​ 

I bought it off eBay so idk what to do

If the seller cannot provide the password, return the system for a refund.  Otherwise, you'll need to factor in a support call (assuming the seller can provide the registered owner's details to you) to the cost of the system.  If the cannot, you'll be purchasing a replacement system board and adding that to the cost of the system.

@ejn63​ I made the password but then it just didn't work at all for some reason so it's probably some random system generated password that I don't know

The system does not generate passwords -- users do.  At this point, your best option is to transfer ownership to your name (you WILL need the current registered owner's contact information to do this).  Once that's done you can call for support (which will cost you a support call fee) to have the password removed.

https://www.dell.com/support/assets-transfer/en-us

@ejn63​ so are you positive a email saying that I bought it off eBay isn't enough evidence that I own it

It won't be, no.  You need to transfer ownership of the system, and for that you need the registration details of the original owner.

Hopefully that is your seller - if so, you're set.  If not, you'll need that from them.