Translation:I read the menu and you read the book.
What sounds the same as what? Are you hearing "N" sounds too?
I've listened to this clip repeatedly, with my eyes closed, but I don't hear anything like an "N" sound at the start of léim or léann.
Even taking account of the fact that the brain can trick us into hearing what we know we should be hearing, I'm pretty sure that this was recorded with an "L" sound, rather than an "N" sound.
"her l's" are standard Irish slender "l"s - the pronunciation of consonants in Irish is affected by whether they are broad or slender. This is most apparent for "s", where slender "s" has a "sh" sound (sé, sí, siúcra, ispíní, éisc), whereas broad "s" has an "ss" sound (scoil, sásta, sú, conas, iasc). In the case of l, it's a bit more subtle, especially for English speakers as the sound of a slender l isn't particularly significant in English, but you can hear a "glide" after the l.
In this case you have two complete complete sentences, and agus is a conjunction joining them, and it means "and".
agus can be translated as "while" in sentences like léim an biachlár agus tú ag léamh an leabhar or léann mé an biachlár agus a bhí tú sa leithreas, but agus doesn't generally mean "while".