Is it one exam or subject?
An ‘A-Level’ stands for ‘Advanced Level’. It’s the CIE qualification most students will be working towards in their final two years of high school, and is what counts towards tertiary study applications. It has two components, known as ‘AS’ and ‘A2’, and you have to sit both to get a subject A-Level qualification - often in your penultimate and final year of school respectively, although this is pretty flexible. Each component contributes 50% to your final A-Level grade, so don’t leave everything to your final year! Most students will sit around 4 A-Level subjects, but you can of course do more if you want to invest more time into your learning.