Ionnsaich← Home
beinnmountainfeminine noun
the
a' bheinn
after a preposition
a' bheinn
of the
na beinne
plural
beanntan
the (plural)
na beanntan

Every form but the headword, the genitive and the plural is worked out by the spelling rules in the grammar guide, so what you see here is what the guide teaches. Awaiting a fluent speaker’s review.