How does the OV2640 Camera Module communicate with arduino and through what pins? My goal is to add one to an arduino esp 32.
As far as I know, Arduino does not have DVP interface peripheral, so you have to implement it yourself. It's 8 or 10 bit parallel port, with Horisontal Synch and Vertical Synchronization pins for signalling when a line or whole frame transmit is done. In addition to that, there's Pixel Clock, which synchronizes all the bits on the port. These usually are way too fast for an 8MHz MCU module (3MHz pixel clock for 1.25FPS @QXGA). In addition to that you need quite a bit of memory to store the image. Setup is done over I2C-like SCCB interface. Datasheet has more details.
If you want somebody to do that for you, take a look at ArduCAM shields