What does ℵ mean in math?

Could you please clarify what the symbol ℵ represents in the realm of mathematics? It's not a commonly encountered notation in everyday calculations, so I'm curious to know its specific meaning and context within the mathematical landscape. Is it associated with a particular branch of math, such as algebra, calculus, or number theory? Understanding its purpose and significance would undoubtedly enrich my comprehension of the intricate web of mathematical concepts.