A strength point in WAoR equals an infantry battalion or a cavalry regiment, so five strength points might be (for example) 3 infantry battalions and 2 cavalry regiments or any other iteration up to the limit of 5 units. IIRC the ratio is set in the army lists for each nation.
WAoR is a very good gaming system and the campaign supplement is an excellent way of managing campaigns, as a bonus it also has very good and manageable siege warfare set of rules. Worth tracking down if 18th C warfare is your bag.