When adding a label to a node (wire) in LTSpice, you can just give it a name like "FOO", or if the label lands on the end of wire stub, you can optionally make it a "connector" of type Input, Output, or Bi-Directional. Note that named nodes have a special significance: two nodes with the same name NOT connected by a wire ARE connected electrically across a page, or hierarchically, in a multilevel hierarchical schematic, provided that it matches a PIN name on the hierarchical symbol.