In some ways it's easier to ascertain to pronunciation of a Kinyarwanda word from it's written form than an English word. Because Kinyarwanda has only been a written language for about a hundred years, the pronunciation of different letters is almost completely consistent throughout the language. Even words that are borrowed from other languages are given a proper Kinyarwanda spelling (e.g. sock → isogisi).
However, Kinyarwanda is a tonal language and the tones can completely change the meaning of a word (e.g. gusura). To be properly understood you will need to learn to distinguish different tones.