Check RAM with free

meteor@pop-os:~$ free -ht
               total        used        free      shared  buff/cache   available
Mem:            31Gi       6.7Gi       8.4Gi       459Mi        16Gi        21Gi
Swap:           19Gi       0.0Ki        19Gi
Total:          51Gi       6.7Gi        28Gi
  • -h for human. Adds units to sizes
  • -t for total. Adds the Total: row.

Or, you can install htop.