"No estudiaré" simply means "I will not study (Spanish)". (Не буду заниматься (испанским).) It does not mean "I won't have learnt (Spanish)". (Не выучу (испанский).) If you want to say "I won't have learnt," you need to use the word "aprender". The Spanish would be, "No habré aprendido español para el lunes que viene." Conversely, if you do want to say, "No estudiaré", then the English version would be, "I won't have studied Spanish by next Monday."