It's a very simple task, you first need to enable SEO Friendly URLs for your store and then make every product url seo friendly.
Part 1: Configure the Site To Accept SEO-Friendly URLs
Step 1: Goto your admin dashboard entering your username/password
Step 2: From the left pane, click on 'Settings > System'.
Step 3: In the right side, click edit icon next to your store name(Your Store(Default) will be displayed by default).
Step 4: Click on 'Services' tab and click 'Yes' in the 'Use SEO URLs' field and save the settings by clicking the 'save' icon at the right top.
Part 2: Change the Product URLs
Step 1: From the left pane, click 'Catalog > Products' and select 'edit' next to the product for which you want to make the URL as SEO-Friendly.
Step 2: Under the 'General' tab, fill 'Meta Tag Title', this is how you request search engines to show your product in the search pages.
Step 3: Under the 'Data' tab, enter your SEO keyword for the product in 'SEO Keyword' field. Remember, whatever keyword you enter in the 'SEO Keyword' field will be converted as your product URL. Spaces in between words will be converted into hyphens('-').
Simultaneously, you can also bulk edit the products through our 'Import / Export' plugin. To know how to bulk edit the products, click here -
Bulk Edit The Products