Keeping your system safe is usually done with the usual antivirus suite or using a current Linux OS (two most common methods I run into.)
The other way to keep your system safe is with backups. Let's say you give me your current boot drive for safekeeping. How long till your system is running again? As in a system drive crash.
I find developers sometimes forgo backups. Usually the newer ones that haven't learned this lesson. Sometimes they think there's another answer because telling them to backup "is not helping."
After that, you can scan the site as others noted at https://www.google.com/search?q=How+to+scan+WordPress+website+for+malwares+and+virus%3F