A pronoun is a shortcut. It saves you having to repeat the same word over and over again in a sentence. Sentences would become very boring and repetitive if we did not use pronouns. Look at this example:
Iain woke up at 7.00am and Iain had a shower. After this, Iain put on Iain's school uniform. Iain ate Iain's breakfast and then Iain caught the bus and Iain went to school.
Let's use some pronouns to relieve the monotony:
Iain woke up at 7.00am and he had a shower. After this, he put on his school uniform. He ate his breakfast and then he caught the bus and he went to school.
Here are the Gaelic personal pronouns and possessive pronouns: