"We are visiting my brother."
Translation:Tha sinn a' cèilidh air mo bhràthair.
Gaelic has many verbs which take a preposition whereby the equivalent English does not. Tadhal is such a verb. In English we would say 'I visited my brother' but in Gaelic it is 'I visited on my brother', 'thadhal mi air mo bhràthair'. Another example is 'ask'. English: 'I asked her'. Gaelic: 'Dh' fhaighnich mi dhith' Literally, I asked of her. Or, English: 'Stop it!', Gaelic: 'Sguir dheth!' ("Stop of it")
It can work the other way too. In English: 'I searched FOR her.' In Gaelic: 'Shir mi i.' No preposition. But, in my experience, this is rare. The only other verb which springs to mind is 'gnog' 'to knock', which takes a Direct Object in Gaelic but a preposition in English.