The stats counter is a WordPress plugin which enables you to add a stat counter block to a page which counts up from zero when the block is visibile in the current browser window.
Download and install the plugin like any other. Once installed and activated you should have a new block available called Stats Counter. Add this to a page and then enter you number into the block content. You can change the duration it takes to count from zero to your number using the box in the insecptor controls on the right.