not sure if I understood correctly lol but yes, Always, because everything is depending on the gender. The main thing is to remember that Slovak language has singular and plural number and three gender forms - masculine, feminin, neutral. the ending of the words thus change depending on the given combination of the grammatical gender
it´s so freaking complicated that I don´t even know how to explain use wiki if you want https://en.wikipedia.org/wiki/Slovak_declension
+ we have one other special thing the kids had to learn, it is called (vybrane slová) litterally translated as - the chosen words - it´s the only words when you have to write y instead of i after b, m, p, r, t, s, v, z and l in all others you have to write i