The sign “understand” have two different meanings. 
1.  “understand” as a verb =  comprehend
2.  “understand” as a conjunction = to clarify
As a conjunction, it can be translated as “but” or "only". 

​The sign “important” have two different meanings. 
1.  “important” as an adjective = essential
2. “important” as a conjunction = to specify 
As a conjunction, it can be translated as “as long as”.



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Examples
Understand
Verb: We understand how to film with the phone.
Conjunction: We will film but with the phone. 

Verb: I understand about eating after exercise. 
Conjunction: I will eat but after exercise.
​Important
Adjective: I saved the important messages, not the videos. 
Conjunction: I saved the messages as long as they are not videos. 

Adjective: I will work with important people. 
Conjunction: I will work as long as it's with people.