Yes. Begin by clicking Products in the main navigation to go to the products section.
There you'll find a Create link on the left. Clicking this will open a window where you can enter in the product data for a new product.
Once the Name, SKU, and Barcode are entered just click Save and Close at the bottom.
Barcodes can be scanned directly into the field after you click the add link.
You'll also find the option to create products in the GPX app as well:
You'll also find that if you are using the "Receiving" option in the GPX app and you scan a barcode that does not yet exist in GroovePacker, you'll have the option to create a new product by adding the remaining data.
If you'll be creating a lot of new products and would like to do so using a spreadsheet please see this article.