As you can see from the photo, Alba means Scotland. There are three languages in Scotland: English, Scottish and Gaelic. Alba is the gaelic word.
Gaelic is a language (and a people) that originated in Ireland and spread to the Isle of Man and Scotland. The three languages are different from each other now, but they do have the same roots and a practised speaker of either of the three should not have too many problems with any of the other. The language spoken in Wales originated in France probably and has therefore much more in common with the Gallic languages spoken in France. So, anybody speaking Scottish Gaelic would not be able to understand Welsh, unless he learned the language!
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