"Tá beagán uisce sa teach."
Translation:There is a little water in the house.
For me "a little water" emphasizes the fact that there's water in the house (but not much). Alternatively, "little water" (without the "a") emphasizes that there's not much (when more might have been expected). What does this usage in Irish emphasize? And how would you say the other form?
The sentence in this example has the first meaning. For the second, you would say something like 'níl mórán uisce sa teach' (there isn't much water in the house).
That is a different sense from the one given in the example. If you wanted to point out a scarcity of water in the house, you could say 'níl mórán uisce sa teach' (there isn't much water in the house).
Sorry, I had to elaborate: this is not really dental dots, but rather the special exception (quote from tips notes):
An exception is that words beginning with d, t, s are not lenited after den, don, sa or san.
den doras off the door sa teach in the house don sú to the juice</pre>
This is covered under the DeNtaL DoTS 'guideline', because 'sa' is a contraction of 'in an'... So the 'n' is virtually there...
What type of word is "beagán"? I would have thought it was an adjective as is describes its associated noun, but it comes before the noun so I assume this is not the case.
Beagán is a noun - that's why it takes an indefinite article in English.
beagán is "a little" in the sense of "a small amount of", it is not the adjective "little"/"small", so beagán uisce means "a little water" in the sense of "a small amount of water", not "a small water", which would be uisce beag.