Is malwarebyte a reliable tool for my MacBook Air's security? I only use it for personal use.

You don't need to install any third party anti-virus apps, cleaning apps, or third party security software as macOS is already secure. These types of apps usually cause more problems than they solve plus they impact system performance. If you believe you may have installed malware on your system, then you can use MalwareBytes to check the system and remove any malware, but you really should not need to even use MalwareBytes. You definitely do not need to use the real-time system scanner. Of all the anti-virus apps MalwareBytes is the only one the advanced contributors will even suggest.