As a particle,
が has several different uses in Japanese. However, each of these different uses share a common theme. That theme expresses ‘highlighting (A) as important, (B)’. In this use,
が comes across as ‘but’, or ‘however’ in English.
This nuance of
が is used directly after any form of verb or
い-Adjective, but requires one of the conjugations of
だ or
です before it when used with a noun or
な-Adjective.
-
毎日(まいにち)走(はし)るが、運動(うんどう)はきらい。
I run everyday, but I don't like exercise.
-
このカレーは辛(から)いが、美味(おい)しい。
This curry is spicy, but delicious.
-
車(くるま)は便利(べんり)だが、危(あぶ)ない。
Cars are convenient, but dangerous.
-
お金(かね)は大切(たいせつ)だが、時間(じかん)も大切(たいせつ)だ。
Money is important, but time is also important.
From these examples, we can see that
が is simply highlighting that ‘while (A) is important, there is extra information’.
が with the meaning of ‘but’ is considered to be very formal, this is due to it sounding quite direct in asserting that there is extra information.
Sometimes a statement will end with
が. In these cases it just means that more information exists, but it is obvious, so it does not need to be said.