One of the official languages in Nigeria is English.
However, while this may sound reassuring, only upper and middle-class people in the largest cities actually speak it, though most citizens have a good understanding of English. The national lingua franca is Nigerian pidgin, an English-based creole language spoken by 75 million people as a second language and by 3-5 million people as a native language, mostly in the Niger Delta. Nigerian pidgin is highly intelligible to an English-speaker to a certain degree, but it will take time to get accustomed to it. However, Nigerian pidgin will not hinder day to day communications. The easiest way to overcome any initial language block is to ask questions. They will not hesitate to ask you to clarify what you mean, or admit that they do not understand an outsider’s particular manner of phrasing. Do not assume that a Nigerian’s inability to answer you indicates ignorance.