The BCBA exam is a computer-based, multiple-choice exam with 185 questions (175 scored and 10 unscored pilot questions).
The exam covers the nine domains of the BCBA Task List, including ethical and professional conduct, foundations of behavior analysis, assessment, intervention planning and implementation, [...]
Each domain has a different weight, with Behavior-Change Procedures typically holding the largest percentage (20%). You can find the specific breakdowns on the BACB website.
The BACB offers a limited number of sample questions on their website. Many third-party resources also offer practice exams and study materials.