You can get a reference to the node object at (or rather close to) a desired set of coordinates by calling the nodes.getClosest function. For example: mdb.models['Model-1'].parts['Part-1'].nodes.getClosest((your_node_x, your_node_y, your_node_z)). You can also enter multiple coordinates in a nested list, and it will return you a list of all requested nodes.
Hi dear sobhan. you can use tools / Query in abaqus toolbar. By doing this, the number of nodes, elements and other structural components of the structure can be easily seen. I hope my explanations are useful and practical. If you have a problem with this, you can contact me.