SQL Server Memory Nodes serve the foundation for SQL Server Memory and they have one-to-one mapping with physical NUMA nodes. For example, if your system has four physical NUMA nodes, your SQL instance will have four Memory Nodes. In case your system does not have NUMA, SQL instance will still have one Memory Node, node 0. Additionally, there will always be one dedicated node for DAC (Dedicated Administrator Connection).
How can you find how many nodes your SQL instance has?
How can you track statistics for each node?
There is perfmon object SQL Server:: Memory Node (I guess, this is a new object since SQL Server 2012)
You can also track node information through DBCC MEMORYSTATUS