"Her apple and his apple."
Translation:A húll agus a úll.
It's not actually considered lenition. It's called "h-prothesis" and is only for a meaning "her" and only if the word starts with a vowel. There's also "t-prothesis" that the ones that generally eclipse use (ár, bhur, a).
Note: "h-prothesis" also happens in other situations, but only with "her" when dealing with possession.
It depends upon whether the noun begins with a vowel or with a consonant. When it begins with a consonant, “his” noun is lenited (where possible) and “her” noun isn’t; when it begins with a vowel, “her” noun receives a prefixed H and “his” noun doesn’t. Thus, a bhanana = “his banana”, a banana = “her banana”, a húll = “her apple”, a úll = “his apple”, and a líomóid can be either “his lemon” or “her lemon”.
The "h" in a chat is what is called séimhiú - modern Irish orthography uses "h" for that, but in older texts the séimhiú was marked with a dot over the "c".
The "h" in a húll is not a séimhiú, because you can't séimhiú a vowel. It's just a h-prefix. For words that start with a vowel, a meaning "his" doesn't do anything, and a meaning "her" causes a h-prefix.
Note that if you spell chat out loud, you should get used to saying cee-séimhiú-ah-tee.
There are two kinds of h’s added: the h that marks lenition and the h-prefix. After “a” meaning “his”, a consonant that can lenite will; however, when it means “her”, nothing happens to the consonant. When “a” precedes a word that begins with a vowel, the “a” that means “his” causes no effect, but the “a” that means “her” prefixes the following word with an h. It’s confusing but there’s a historical reason that can’t be seen except for these weird lenition and prefixing rules.
"A" means "his/her/its/their" while "thy" in Early Modern English only meant "your" for the singular. The way to discern the mean of "a" in Irish is the way it affects the following noun. "A" meaning "his/its" will lenite a noun if it begins with a consonant that can be lenited and it does nothing to nouns beginning with a vowel. "A" meaning "her/its" does nothing to nouns beginning with a consonant and adds an h to nouns beginning with a vowel. (Remember that in Irish, it is either sé or sí depending on the gender of the noun.) "A" meaning "their" has the noun go through eclipsis (I have no idea to phrase the act of eclipsis properly lol) and addes an n to nouns beginning with a vowel. The h becomes part of the word while the n is hyphenated. Example: a chara, a cara, a gcara; his friend, her friend, their friend; a úll, a húll, a n-úll; his apple, her apple, their apple. The only problem is words that begin with letters that can't go through lenition or eclipsis so context is your only help their.