Free memory counter in PerfMon

Just want to make sure I am understanding this correct. Say I have set my maximum server memory according to best practice. Now I see in the the PerfMon counter: SQLServer: Memory Manager - Free memory Many Gigabytes (of free memeory). Does this mean that I can increase my "max server memory (MB)" until e.g. only a few MB is left (i.e. the Free memory counter only shows a few MB)?