What does the Latin end ibus mean?

Latin nouns can be divided into a stem and an ending. When creating the different cases, usually only the ending is changed, while the stem remains the same:
Nominative singular: dominus
Nominative plural: domini

This also applies to many other Indo-European languages:
Nominative singular: Herr, homme
Nominative plural: Mr.en, hommes

Latin distinguishes between 5 classes of declination:

casea-Dec.o-Dec.Cons. Decl.u-Dec.e-Dec.
importancemistressMrkingportDay
Nominative singulardominadominusrex (s)portusdiit
Accusative singulardominat thedominaroundregemportarounddiem
Genitive singulardominaedominiregisportusdiegg
Dative singulardominaedominOregiportuidiegg
Ablative singulardominadominOregeportudie
Nominative pluraldominaedominiregitportusdiit
Accusative pluraldominasdominosregitportusdiit
Genitive pluraldominarumdominorumregaroundportuumdierum
Dative pluraldominisdominisregibusportibusdiebus
Ablative pluraldominisdominisregibusportibusdiebus

The case ablative no longer occurs in many modern languages. He answers questions like "where?", "When?", "Where from?", "From what?", "With what?", "With what?", "With whom?", "How?", "Why?" ".