FR4 is the standard fibreglass-epoxy base for general use PCBs.
TG135 is the 'Glass Transition' temperature (135°C) - above this the board softens.
1/1oz means 1oz of copper per square foot (that's 34.8µm thick), double sided
HASL is Hot Air Solder Levelling: The etched PCB is dipped in molten solder and the excess is levelled (blown off) by hot air jets.
1.6mm is the thicckness (standard for single and double sided)