This MATLAB code seems to be used to detect faces in real time in the camera. Let me help you explain the functions of each part:

Clc: Clears all output on the command line.

Clear All: Delete all variables.

Close All: Close all graphics windows.

Web = webcam (): Create a webcam object.

Pic =web.snapshot: Capture images with webcam objects.

Det face = vision. Cascade object detector (): Create a face detector.

Imshow(pic): display images.

While true: starts an infinite loop.

Pic=web.snapshot: Capture images with webcam objects.

Pic2=rgb2gray(pic): converts the image into a gray image.

Bbox = step(detface, pic): Use the face detector to detect the face in the image.

Img = InsertObject annotation (PIC, ... rectangle', BBOX,' face'): marks the detected face in the image.

Imshow(img): displays the marked image.

I hope these explanations will help you understand the function of the code.