General Abilities are abilities that any character can select. As with all Abilities they cost 1 XP to purchase and you can only purchase General Abilities from a Rank that you have access to from your Class (e.g. if you are a Startouched then you cannot access Rank 3 General Abilities until you have access to Rank 3 Startouched Abilities). You may purchase from as many different General Ability trees as you like.
General Abilities represent the mundane or readily available training that any explorer in Planetfall may have - more esoteric but non-class-specific Abilities are more likely to be Experimental Abilities instead.