Literally it means "a timeless being whom never dies." The first word Akal, literally timeless, immortal, non-temporal, is a term integral to Sikh tradition and philosophy. It is extensively used in the Sri Guru Granth Sahib and Dasam Granth hymns by Guru Gobind Singh, who titled one of his poetic compositions Akal Ustat, i.e. "In Praise (ustati) of the Timeless One (akal)". However, the concept of Akal is not peculiar to the Dasam Granth. It goes back to the very origins of the Sikh faith.
Together the two words mean the "Timeless, eternal being".