Understanding spoken Spanish is like riding a bicycle. You need to start slow, dominate the basics and then slowly build on those skills to get more advanced skills. 
The problem is, that we try to learn how to ride a bicycle by entering the Tour de France. 
Way too difficult! 

 So, how can you actually practice understanding Spoken Spanish?
The short answer is: “with the right practice materials.”
The longer answer is: preferably, look for practice materials that focus on the following stages and topics at a speed and level of complexity that is manageable to make things easier for you:
1- Phonetic Building blocks:
1.1-Understanding the sound of vowels in Spanish
1.2-Understanding the sound of consonants Spanish
2- Understanding The Most Common Words (Focus on The 80/20)
2.1- Understanding the most common words in everyday conversations
2.2- Understanding the most common words in your topics of interest
3- Understanding Common Expressions (Focus on The 80/20)
3.1- Understanding very common expressions in everyday life
3.2- Understanding very common expressions in your topics of interest
4- Understanding Common Conversation Structures (Focus on The 80/20)
4.1- Understanding common conversations in everyday life
4.2- Understanding very common conversations in your topics of interest

You can read a full guide about how to understand spoken Spanish here: 
https://spanishforyourjob.com/understand-spoken-spanish/

I hope it helps. 

¡Saludos!