1. Explain the difference between CALCULATE and CALCULATETABLE in DAX.
CALCULATE evaluates an expression in a modified filter context and returns a single scalar value. CALCULATETABLE does exactly the same but returns an entire table of rows instead.
2. What is Row-Level Security (RLS) in Power BI?
RLS restricts data access for given users. Filters restrict data at the row level based on roles you define. For example, a regional manager can only view records mapped to their specific state.