The pH of a solution measures the amount of hydrogen ions that are in a solution. The term "pH" literally means "the power of hydrogen." The pH of a substance tells how acidic or basic a substance is.
A pH of 7 means that a substance is neutral, so it is neither an acid nor a base. A reading of less than 7 means that the substance is acidic, whereas a measurement of greater than 7 means that the substance is basic. The more extreme the reading is, the more acidic or basic a solution is. For example, a substance that triggers a reading of 1 on the pH scale is extremely acidic. On the other hand, if a chemical has a pH of 14, it is a very strong base.