The Spanish phrase "buscar número de teléfono" roughly translates into English as "look up the telephone number". Note that "buscar" means "search", not "look" in the sense of watching or viewing.
The Spanish phrase "buscar número de teléfono" is an imperative, instructing someone else to look up a telephone number. However, English speakers should be forewarned that "buscar" is not the general Spanish verb for looking; outside of the idiomatic expression "look up," meaning to search, the Spanish verb meaning to look is "mirar".
The Spanish word "teléfono" is a cognate of the English telephone, but is not a direct borrowing from English. Both words are actually borrowed from French. The original French word, "téléphone," predated the invention of the phone by Alexander Graham Bell. Instead, it denoted a system of communication using musical tones.