The verb 会 (huì) can be used to express ability that has been learned, i.e. a skill. In this case 会 is an auxiliary verb. This structure is the easiest way to express all kinds of skills, from languages, to sports to skills in daily life such as cooking and driving.
The basic structure for 会 is:
他 会 说 中文。
Negating 会 sentences
会 sentences are negated with 不, which is inserted in front of 会:
Again, this is the simplest way to express the lack of a learned ability. Examples:
我们 不 会 说 德语。
Note that if we say 我不能说德语 the speaker is saying that he can’t speak German for some reason other than his own ability, perhaps because speaking German in Chinese class is forbidden.