I am selenium python and I would like to speed up my tests. let's say 5 tests simultaneously. How can I achieve that on the single machine with the help of selenium grid
You won't need a Selenium Grid for this. The Grid is used to distribute the test execution across multiple machines. Since you're only using one machine you don't need to use it.
You are running tests so I'm assuming you are using a test framework. You should do some research on how you can run tests in parallel using this framework.
There will probably also be a way to execute a function before test execution. In this function you can start the driver.
I'd be happy to give you a more detailed answer but your question is lacking the framework you are using to run the tests.
How to Speed up Test Execution Using Selenium Grid on single machine