"I am not wanting two buses."
Translation:Chan eil mi ag iarraidh dà bhus.
Anything more than one is plural in English. Gaelic has singular, dual, and plural. A noun following dà does not take the plural form, and dà lenites the word that follows it. This is explained in the unit for Numbers or on the complete notes for the course at Duome in case you can't access the notes in the units (if you are using your phone, for example). https://duome.eu/tips/en/gd .