"And We placed therein lofty, firm mountains," meaning: the high mountains. "And We gave you to drink sweet water," fresh.
﴿وَجَعَلنَا فِيهَا رواسي شامخات﴾ يَعْنِي: الْجِبَالَ الْمُرْتَفِعَةَ ﴿وَأَسْقَيْنَاكُمْ مَاءً فراتا﴾ عذبًا