"She has eleven."
Translation:Tha aon deug aice.
Dà lenites the initial letter of the following word if that word starts with one of the usual lenitable consonants - so dà dheug.
Aon lenites the usual consonants except d, n, t, l, s ("dentals" is a good way to remember them), so aon deug.
This is called "blocked lenition" and doesn't really get discussed in the tips (probably too complicated at this stage) - basically, if one of d, n, t, l or s at the end of a word collides with a d, n, t, l or s at the beginning of the next word, lenition traditionally doesn't happen where you would otherwise expect it to (you'll see blocked lenition in action in the definite article with feminine nouns beginning with d, n, t, and l and in "is tusa", etc. ). To make matters more complicated, that rule is breaking down in some circumstances. Here is a link if you want to explore things further: http://akerbeltz.org/?title=The_homo-organic_rule_or_When_not_to_lenite
But at this stage it's probably easier just to remember aon deug, dà dheug without overthinking it.