In rhythm, consecutive events aren't equal in strength.
They generally alternate; strong-weak-strong-weak, ...
This doesn't necessarily mean that notes that fall on strong positions are played louder (they often are), but that one rhythmic event is felt more strongly than the following.
Since this alternating "strong-weak" pattern exists at the half note, quarter note, eighth note and sixteenth note levels, every rhythmic position in a bar has a slightly different weight.

Musicians can override this natural feel by placing voluntary accents on weak rhythmic positions.

There are two ways to perform the exercises:

•Vocally: Using the syllable "Ta" (recommended).

•Manually: Using your hand, finger, nail, a pencil or a stick.