You can add social share buttons at the single product page, making use of Jetpack’s Sharing module. You simply need to Install and activate Jetpack, and enable the Sharing module. You can find more details on setting the button’s appearance here: https://jetpack.com/support/sharing/
Below is a screenshot of the settings we have used at the demo. This page is located under Settings > Sharing and through it you can setup which social buttons display and where. Note that in the specific screenshot we have the sharing icons show up in both posts and products.