I need a OS to use word, excel
Hi Jairo, and welcome! Your needs for Word and Excel can make a difference. If you have macros embedded in any of your files, then the Linux office programs will not handle them (LibreOffice is the most popular). If you use the more modern .docx and .xlsx formats from Microsoft, you may be okay or maybe not.... you would just need to test some of your documents to see if LibreOffice can open them cleanly and maintain the formatting. Standard Excel formulas should probably be fine, but again, you should test any files that may be critical.
It is far better to use the Linux office programs, such as LibreOffice... but there are a few others available too. Linux is not Windows, and it will not easily install Microsoft Office. There is some chance of using older versions of MS Office, but even those may not work well.
Before committing to erasing Windows from your computer, you should take some time to test Linux to see if it's right for you. There's a couple of ways to test it out. One way is to install VirtualBox in Windows if you have a fair amount of RAM. VirtualBox will then let you install Linux inside of Windows itself, and you can install 2 or 3 or more until you find what you like, and you can delete them all when done testing. Another way is to install Linux on a "live" DVD or USB flash drive. You can then boot your computer on the DVD or USB so it runs Linux and Windows is never even started.... but running on a DVD or USB is a little slower than running on a hard drive.
Neither of these methods are perfect, but they are a good way to start experimenting. You can find TONS of information with Google on how both of these methods are done, including videos on YouTube to help show you the steps. But when you have Linux running, you can then test out your Word and Excel files to see if they will be okay.
Cheers