If you work on an environment without internet, only way to install software is using RPM package which you can download from a pc with internet and transfer the rpm file via usb pendrive to the server without internet.
To install RPM package, there are 2 way to do it.
First method – install the RPM Package via yum command
yum localinstall packagename.rpm
Second method – use rpm command to install
rpm -i packagename.rpm
rpm -ivh packagename.rpm
-i : install a package
-v : verbose
-h : print hash marks as the package archive is unpacked.
Querying RPM Package File
rpm -qi packagename