There are many security plugins that provide firewall protection to prevent unauthorized access to your website. It includes preventing XSS and SQL injection attacks, which are popular hacking attempts.
In some plugins, malware scanning features are included that check your site for suspicious files or code that may indicate a malware infection.
Backups, alerts when a change is made to the database, and security checks to ensure the database is not vulnerable are features of database security.
Plugins can monitor for brute force attacks and block attempts to guess passwords, some can also add Captcha, reCaptcha or honeypots to protect login and registration forms.
SSL/TLS encryption can help protect data transmitted between your site and visitors by encrypting it so it cannot be intercepted by hackers.
Two-factor authentication adds an extra layer of security to your site by requiring users to enter a second form of identification in addition to their password, such as a code sent to their phone.