Explain First Normal Form and provide examples

What will be an ideal response?

The First Normal Form removes repeating groups and arrays. If a column in a Customer table, for example, contained multiple phone numbers, that would be an array. If it contained multiple columns named something like "Phone1", "Phone2", etc., that would be a repeating group. To make the table conform to First Normal Form the phone numbers should be placed in another entity with a relation to the Customer entity.