The third declension includes feminine nouns with zero endings and the word “мати” (a mother).
It does not have groups like the first and second declensions and thus is easier to deal with. Many feminine nouns from this group mean something abstract, object's quality, condition, action or even some general concepts. These nouns often cannot have plural form.
Example: сміливість (courage), гордість (pride), любов (love), щастя (happiness), мудрість (a wisdom), радість (a joy) etc.