Short answer: Yes, the Aztecs knew about lands outside their borders because of trade. There's evidence of trade routes connecting North America, Mesoamerica, and South America dating back to at least the Classic Maya.

However it's likely that the knowledge they had was indirect or secondhand. How much knowledge they had, or the extent of their knowledge is harder to determine.

• Here and here are some quick and dirty overviews with specific trade goods mentioned (neither piece is cited so take them at face value)
• Visualization of trade routes
• Older post addressing something similar with a much more detailed answer from u/Mictlantecuhtli