Google:
"how to import contacts from excel to WhatsApp"
There are many apps, tools, converters, etc. that will show up no matter what criteria you use.
Look at current links (I use 1 year as "current") and look at the source websites. Visit a few but do not immediately download or launch anything.
Lots of misleading sites that will try to trick you into downloading other stuff....
Bookmark sites that seem relevant and legitimate. Both words are subjective but after visiting a few websites you will quickly get a sense of which ones are likely to provide a real solution.
Any sites that make you uneasy or uncertain - just leave. Watch out for fake "out of date" errors, etc..
When you are ready to try something be sure that the...