From where you grab that image ? From host, cluster or virtual machine ? Assuming you get from a cluster, from memory perspective you're able to use up to 21,6GB without affect the buffer and HA on that particular cluster.
Looks like this is a VM you have selected. Based on that you are correct. Vrops is saying that you can reduce the memory of the vm to the recommended size. There is one big thing you need to take into consideration. That stat is based on demand on the host and vrops OOTB has no idea what the application is doing inside the VM. If the application has reserved all the memory inside the vm for caching (SQL server for example) vrops wont report that because it can only tell what memory the VM needs on the dost (demand).
In short you need to know the workload of the VM and how it interacts with memory before you reduce anything as you could cause problems with application performance