Google itself is safe, like almost every search engine. However, it is not the search engine itself that you should worry about. It is the links that it can lead you to. You could look for free extensions for chrome on google search engine, but it could lead you to a website loaded with viruses. Be careful when visiting sites that you found on the google search engine. Google has no virus blocker. It cannot tell if the website has a virus or not.
The image and video section of google, though quite useful, may give you obscene pictures. Be careful about letting your child on Google without a child-safety extension. Even if you search for something non-obscene on Google Images, it may find something obscene that is related to whatever you searched, that is offensive.
However, in spite of all I said in this comment, Google is a good search engine, just be careful about going to random sites that you found on Google.
I apologize for the length of this comment, but I had a lot to say about this website.
Thank you for reading. Stay safe from malware! :-)