Literally means servitude / submission. Most commonly translated as worship. 

The terms ‘acts of ʿIbādah’ refer to acts of worship such as salah (prayer), du’a (supplication), sawm (fasting), etc. However, any permissible action can become ʿibādah when performed with the intention of pleasing Allah

For Muslims, performing ʿibādah is life’s purpose, and we strive to make our lives one sustained act of ʿibādah.