hopefully I’m asking this question in the right place. I also hope that I’m using the correct terms.

How would I go about doing this?:

I’m Working on a poster and the background is white and in the middle theres a shape. The shape is purple (or any other color). Let’s say i have text that is the same color as the shape. So the text goes through the shape. The text inside shape in the middle disappears because its the same color. Lets say I want it to be white the same color as the background. How can i change the color without doing it manually? is it a blending technique i have to use? what would be the best way to achieve that since it does involve a lot of text and some letters are caught between two colors.

thank you.