User blog comment:Mich, Michele & Kuhla/Future Units Preview/@comment-10070597-20160330225655/@comment-26944381-20160331010854

The first is about the effects added to the units itselfs or their BB/SBB/UBB, ex: Vargas can get crit damage and crit rate to BB/SBB or boost his own parameters.

The second, kinda obvious but... you need your unit to be Lv. 150 with SBB 10 (UBB and ES unlocked) to unlock the one above.