This is the 15182nd most frequent Russian word.
помешать
To hinder, interfere, or stir (depending on context).
In this sentence, 'помешать' indicates causing an inconvenience or a disturbance to someone during an activity.
Я не хотел тебе помешать во время работы.
I didn't want to disturb you while you were working.
Here, 'помешать' is used in the context of mixing or stirring a substance to combine it.
Добавьте сахар в чай и помешайте.
Add sugar to the tea and stir it.
In this example, 'помешать' means to obstruct or hinder progress or achievement of something.