contours, _ = cv.findContours(binary1, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)

This line of code uses the OpenCV library to find contours in a binary image.

- The first argument, "binary1", is the input image. It should be a binary image with white objects on a black background.
- The second argument, "cv.RETR_TREE", specifies the retrieval mode for contours. This mode retrieves all of the contours and reconstructs a full hierarchy of nested contours.
- The third argument, "cv.CHAIN_APPROX_SIMPLE", specifies the contour approximation method. This method compresses horizontal, vertical, and diagonal segments and leaves only their end points. For example, a rectangle contour would be represented by only 4 points instead of a series of connected lines.

The function returns two values:
- "contours" is a list of all the contours found in the image, each represented as a list of points.
- The second value is not assigned to anything, so it is discarded. It represents the hierarchy of contours, which is useful for understanding how contours are nested within each other.