nebylo jediné šlápoty

Gramatika: jediné šlápoty is in the genitive case. The verb, not having the grammatical subject in the nominative case, takes the neuter singular form. This use of the genitive case in a sentence reporting the absence of something is archaic now. In contemporary Czech the genitive reporting non-existence of something is used in very limited fixed expressions such as není divu, že... "It is not surprisng that..." Otherwise, the nominative case is used: nebyla jediná šlápota

anglicky: there was not a single footprint