The language spoken by the largest number of people in the world is

Mandarin Chinese (often referred to as Chinese or Putonghua) is the language with the largest number of native speakers worldwide, and is therefore the best answer to this question. Compilations that count first-language (native) speakers place Chinese/Mandarin at the top of the list. Ethnologue‑based summaries report roughly 1.2–1.3 billion native Chinese speakers, making it the single largest native‑language population globally [1]. Note that rankings can differ if one counts total speakers (native plus second‑language): some sources list English first by total speakers, but for the standard interpretation of “largest number of people” as native speakers, Mandarin/Chinese is correct.

Sources

1. [1] https://indianexpress.com/article/explained/telling-numbers-chinese-most-widely-spoken-2-indian-languages-in-top-10-5632836/