Inability to correctly pronounce words of a foreign language comes from not having experience with the target language's sound system. The number of syllables that exist in the person's language has little to do with it. What is more important is the perceptual distance between the sounds of the native and target languages, and the rules of combination in the two languages.
Some languages have the vowels [ø] or [ɯ], many do not. If the target word contains the vowel [ɯ] and you don't know how to pronounce [ɯ], you are probably not going to pronounce it correctly. If the target language has [o] and your language only has [ɔ], your pronunciation will probably be incorrect, but pronouncing [ɔ] instead of [o] is more likely not to be noticed than, say, pronouncing [ɯ] as [u]. The consonant [ʕ] is rather challenging and most people cannot get it correct, in fact even if you speak a language that has that consonant, you may still sound "wrong" because the actual pronunciation of [ʕ] varies substantially between Tigrinya, Chechen, Moroccan Arabic, Iraqi Arabic, Somali and Kalispel. A native speaker of German can probably distinguish a native speaker of German saying Haus, weiss as opposed to an English speaker saying house, vice.
Even if you can correctly articulate all of the individual sounds of the target language, there may well be rules of sound combination that interfere with production, especially when a person's native language has only a subset of possible sound combinations. English speakers have a very hard time pronouncing words that start with [mb, nd, ng], which is a very common initial sequence in African languages. They also have a hard time producing long arbitrary-looking consonant sequences like Polish [fstʂɔŋs] or Georgian [ɡvbrdɣvnis]. The lack of experience with such combinations, or any sufficiently-similar sequences, makes such words hard to pronounce.