As for sounds, languages differ in two aspects: what contrasts they recognize among spoken sounds (phonemics) and how those sounds are actually produced (phonetics). When native Spanish speakers who don't also speak English have to produce an English word, these two will act in succession (forgetting for the moment the matter of orthography).
First the Spanish speaker will try to match the English sounds to the Spanish phonemic system. English has more consonants than Spanish and many more vowels, so the matching process will discard many English sound contrasts from the get-go. For example, in British English craft is pronounced with a long low back vowel, /ɑː/, while in the US it's pronounced with a short low-mid front vowel, /æ/. These have no phonemic counterpart in Spanish, they'll be conflated as /a/. Depending on the speaker and the dialect, even the low-mid back vowel /ʌ/ of cruft will be mapped to Spanish /a/.
The same goes for short and long /ɪ/ and /iː/ (as in tin and teen), which will be mapped to Spanish /i/, and for the schwa, which might end up as /a/ or maybe /e/ (beer /bɪə/ or /biːɹ/ will probably end up as /biar/).
Once this mapping has taken place, there comes the second part: adapting the phonetics. Spanish speakers might recognize a phonemic contrast and employ it, but the actual realization of the sound might not be the same as in English. For example, both languages have two series of stops, voiceless and voiced, /p t k b d g/, which are readily recognizable, but they don't realize them in the same way. English voiced stops remain stops between vowels, but Spanish turns them into fricatives; English voiceless stops are initially aspirated, while Spanish ones are not. That's why Spanish speakers sometimes render two as [tʃu] (as if they were pronouncing a Spanish word chu): because aspiration is not something Spanish has. Furthermore, English stops /t d/ are alveolar, while Spanish /t d/ are dental. And the English r has a handful of possible realizations, none of which coincide with the Spanish alveolar tap (the r in toro).
Spanish also has a more restricted syllable structure (phonotactics), so upon encountering an English word like craft, Spanish speakers will tend to simplify it to something like *craf (no Spanish words have a final /f/, but it's easy enough to produce one).
All of this assumes the Spanish speaker in question has no experience of hearing English and/or training in English pronunciation, which, depending on the region, socioeconomic status and the like, might be more or less unlikely.