As a tester you need to understand what the different challenges in testing stream as you will need to overcome the same

1. STLC process related challenges :
   1.1 Limited time available for testing, Late engagement of testing team
   1.2 Test environment issues
   1.3 Delays in defect fixing / imporper fixing of defects resulting in impacts
   1.4 Lack of or insufficient knowledge level of testing team - Application knowledge / domain knowledge / tool knowledge level / experience level
   1.5 Communication issues like unresolved queries, delay in response, communication hurdles with development team
   
2. Application Related Challenges :
   2.1 Changing Requirements
   2.2 Limited documentation of application features
   2.3 Non availability of right set of test data
   2.4 Build quality issues
   2.5 Show-stopper defects