For actions that are continuous, e.g., eating, running, dancing, etc., with “naka”, they only mean that the doer of the action was able to complete it. ------
Ang bata ay nakakain na. = The child has eaten/was already able to eat. ------
Nakakain sila. = They were able to eat. ------
Ang magnanakaw ay nakatakbo bago dumating ang pulis. = The thief was able to run away before the police came. ------
Buti na lang at nakasayaw ka kahit masakit ang paa mo. = Good thing you were able to dance even if your foot hurts. ------
Note: “I’m eating” is not yet a completed action, therefore, you can’t use “naka” in that sentence. “I’m eating” is “kumakain ako” or “ako ay kumakain”.