The noun patience can be countable or uncountable. In more general, commonly used, contexts, the plural form will also be patience. However, in more specific contexts, the plural form can also be patiences e.g. in reference to various types of patiences or a collection of patiences.

What is the singular form of patience?

Patience is a noun and is a human character trait. Its adjective form is patient. Patients is the plural form of patient. They are both nouns.

Is it patience or keep patience?

There's room for confusion here, so let's make this simple: You can be patient, because patient is an adjective; You can have patience, because patience is a noun; You can be patience personified, but it's not very easy to achieve; You can't have patient; Patients is the plural of the noun patient, a person who is ...