'Radiallaha anha' and 'Radiallahu anhu'

'radiallahu anhu' means 'Allah's blessings be on him' while 'radiallahu anha' means the same thing,
only for women i.e. 'Allah's blessings be on her'. the addition of 'ha' signifies female gender.

for instance, 'Abu Bakr radiallahu anhu' in contrast with 'Aisha radiallahu anha'
blessings here means Allah's acceptance on everything that they do.