In the Arabic language, the basic meaing of Salah is supplication. In religious terminology, Salah is used to refer to the acts of bowing and prostration, the remaining specified acts associated with it, specificed at certain times, with those known conditions, and the characteristics, and requirements that are well-known about it.
﴿وَالَّذِينَ يُؤْمِنُونَ بِمَآ أُنزِلَ إِلَيْكَ وَمَآ أُنزِلَ مِن قَبْلِكَ وَبِالأْخِرَةِ هُمْ يُوقِنُونَ ﴾
(4. And who have faith in what is revealed to you and in what was revealed before you, and in the Hereafter they are certain.)
Ibn `Abbas said that,
﴿وَالَّذِينَ يُؤْمِنُونَ بِمَآ أُنزِلَ إِلَيْكَ وَمَآ أُنزِلَ مِن قَبْلِكَ﴾
(And who have faith in what is revealed to you and in what was revealed before you.) means, "They believe in what Allah sent you with, and in what the previous Messengers were sent with, they do not distinguish between (believing) them, nor do they reject what they brought from their Lord.''
﴿وَبِالأْخِرَةِ هُمْ يُوقِنُونَ﴾
(And in the Hereafter they are certain) that is the resurrection, the standing (on the Day of Resurrection), Paradise, the Fire, the reckoning and the the Scale that weighs the deeds (the Mizan). The Hereafter is so named because it comes after this earthly life.