In short: if it’s a neuter noun then the ending in plural form is -a (1 piwo – 2 piwa)if it’s a masculine or feminine noun:– and the last consonant is -k- or -g- then the ending in plural form is -i (1 wódka – 2 wódki)– and the last consonant is ń, ni, sz, cz, rz/ż, l, j, c, dz, ś, ć or ź than the ending in plural form is -e (1 tokaj – 2 tokaje)– and the last consonant is any other letter then the ending in plural form is -y (1 miód – 2 miody) And here are examples.