Learning some novel word, both the child and adult must create its representation in the mind. It involves different levels of language processing. In particular, the phonological representation responsible for the sublexical features of the novel word (associated with the statistical distribution of phonemes and their sequences), plays a crucial role in this process because it refers to basic information about the acquired vocabulary. The aim of this paper is to present how the phonotactic probability affects language processing and learning novel words in native and foreign language. On the basis of reviewed research, practical solutions for education and developmental diagnosis are proposed.