The pH scale is used to measure the acidity and basicity of solutions on a scale of 0 to 14. At the low end of the spectrum are acids such as battery acid and lemon juice, while at the high end are bases including ammonia and lye. In the middle are neutral solutions, which have a pH of 7.
Litmus paper, or red and blue test strips, will tell you whether a solution is an acid or a base, but it won't give you information about the strength of the solution. Universal, or alkacid, indicator paper has a different color to match every number on the pH scale. Neutral solutions turn the paper green.
Put a few drops of water onto universal paper and it will turn a bright kelly green. Other common neutral solutions include sodium chloride or table salt and sugar solutions.