Translation:Her bringing up
Ei masculine causes a soft mutation. Ei feminine causes a aspirate mutation. This only works for the letters, T, C, P, D, G, B, Rh, M, Ll (for soft mutations), and T, C, P(for aspirate mutations) but otherwise it's easy to assume from the general context of the conversation.
My understanding is that the difference is at the end, you differentiate "his" or "her" by "e/o" or "hi", but when this part is omitted (which seems like they can), you will only be able to tell it's third person singular without context. see https://cls.byu.edu/welsh/101-Possessive_Chart.html
I could be deadly wrong on this as I am also learning Welsh so I hope someone could jump in and confirm it :D
This is kind of true, in terms of if the pronoun is omitted then if the word starts with a letter that can't be mutated e.g a vowel or s etc then you can't tell but if the word starts with a T, C, P, D, G, B, Rh, M or Ll and it mutates softly then you know it's masculine, and if it starts with one of these letters and it has mutated aspirately (for T, C or P) or not mutated at all (for D, G, B, Rh, M, Ll) then you know it's feminine.