Resurrection (Ba^th) is the rising of the dead from their graves after they are brought back to life; after their decayed bodies are recreated, if they were among bodies that decay. Some bodies do not decay, and those are the bodies of the Prophets, battlefield martyrs the bodies of some of the righteous Muslims (awliya’). Allah said in Surat al-Hajj verse #7:

﴿وأنّ الساعة ءاتية ٌ لا ريب فيها وأنّ الله يبعث من في القبور﴾. سورة الحج.

The verse means: [And, that they may know, that the Day of Judgement is coming – no doubt about it – and that Allah will resurrect those in the graves.]