OID are usually translated using a “dictionary” or MIB, that should be properly installed. In the latest versions of Ubuntu/Debian those MIB aren’t pre-installed on the system, and you need to install/download them explicitly.
To do this, you can download a package called snmp-mibs-downloader and install it. After installation, edit the file /etc/snmp/snmp.conf and comment lines that start with mib :. It should work.
After that, restart your Apache server. For example on Ubuntu:
sudo /etc/init.d/apache2 restart
Note: for Ubuntu 20.04 just add mib : lines that you need.
