Learn French: Je ne pense pas que ce robot autonome puisse comprendre ce que je dis. - I don't think that this autonomous robot can understand what I'm saying.

Puisse is the subjunctive form of pouvoir (to be able to / can). In French, verbs of opinion like penser (to think) and croire (to believe) take the indicative mood when they are affirmative. However, when they are negative, like je ne pense pas que in this sentence, they express doubt or uncertainty. This shift to uncertainty is exactly what triggers the subjunctive.

If I change the sentence to be affirmative ("I think that..."), does the verb change?

Yes! If you remove the negative ne... pas, you are stating a belief as a fact, so the doubt is gone and you no longer use the subjunctive. The verb goes back to the standard present indicative: Je pense que ce robot autonome peut comprendre ce que je dis.

Puisse looks very different from the regular present tense of pouvoir. Is it an exception?

Yes, pouvoir has a highly irregular subjunctive stem. While most verbs form their subjunctive stem by dropping the -ent from the ils/elles present tense form, pouvoir uses a completely unique base: puiss-. You then add the regular subjunctive endings to it, which is why we get puisse for the il/elle/on form here.

Why does the sentence use ce que for "what" instead of quoi?