Wide shoes are in regard to the width of the feet.
In summary a wide width shoe would have the same length as a regular sized shoe but the forefoot and possibly the toe area would have a wider width. The wider width footwear is manufactured to accommodate wider feet.
Unfortunately, the footwear industry does not have an exact standardization in regard to sizing of shoes. Each brand may have their own measurements. Many shoe brands utilize a letter system for shoe width sizes.
Some of the examples:
If your shoe fits in regard to length but they feel snug around the foot, you may need to try on some wide width shoes.
Learn more about shoe size measurements.