The plugin adds SMS capability to WordPress. You can send SMS to individual users or lists, let visitors subscribe to an SMS newsletter, and trigger a text message for practically every event that happens in WordPress - a new user, a new post, a form submission or, with WooCommerce, every stage of an order. Messages are delivered through your SMSGatewayHub account over TRAI DLT-registered routes.
For WooCommerce stores, SMS is the fastest way to confirm orders, share shipping updates and reduce cash-on-delivery refusals, because customers read text messages within minutes. The Pro edition plugs into WooCommerce, BuddyPress, Gravity Forms, Contact Form 7, Easy Digital Downloads, WP Job Manager and more, so you can automate messages without custom code. For setup screenshots, see the WooCommerce SMS gateway document.
Developers can still extend it: both editions expose a REST API and webhooks, and anything the plugin cannot do can be built directly on the HTTPS SMS API.