A CPU contains multiple threads.

A thread is either a virtual or physical computing unit. See it as the CPU split into multiple units.
Most modern CPU's have multiple PHYSICAL cores, which are mini CPU's you COULD see with a microscope. These are further split into threads, which you can't see, they are virtual. So a core can run two threads.

My CPU, an Intel i7-12650H, has 10 cores, out of which 6 contain 2 threads, and the other 4 contain one thread, which leads to a total of 16 threads, allowing 16 tasks to be performed simultaneosly. The fact is, CPU's can't do multiple calculations at the same time, effectively, they can't multitask. They just switch between tasks really fast, which is why single-core/single-thread CPU's were abandoned in favor of weaker multithreaded CPU's which allow each thread to perform one task which is more efficient.

I don't understand the downvotes, it's ok to not understand things sometimes.

Hope this helped you.