Spanish has three nasal phonemes:

• The bilabial nasal /m/ [m] mama (mum), cama (bed)
• The alveolar nasal /n/ [n] no (no), cana (grey hair)
• The palatal nasal /ɲ/ [ɲ] ñandú (rhea), caña (cane)

English does not have a palatal nasal. It is commonly compared to the intervocalic sound in words like onion and canyon. Native speakers of English generally need a fair amount of practice before they master “la eñe”.

The distribution of nasals, however, is somewhat deficient in Spanish. In word-final position only the alveolar nasal is present. So borrowings that end in /ɲ/ or /m/ are generally adopted into Spanish with a final n, e.g. Adam -> Adán, champagne -> champán. In some varieties in Western Spain and in the Caribbean, word-final nis pronounced velar [ŋ], the sound at the end of singing.

Nasal assimilation

Nasals in pre-consonantal position, that is in syllable-coda (both within the word and across word-boundary), assimilate to the place of articulation of the following consonant. 

• A nasal before a bilabial sound /p/ or /b/ is pronounced bilabial [m]; ambos (both), u[m] beso (a kiss).  It’s worth pointing out that the orthographic sequence -nv- also represents phonetic [mb] as in convertir [kombeɾˈtiɾ], invitar [imbiˈtaɾ].
• Before labiodental f, the nasal becomes labiodental [ɱ] énfasis (emphasis).
• Before dentals, the nasal is pronounced dental [n̪], cantar (to sing). It sounds very similar to alveolar n, but the tip of the tongue touches the back of the front teeth, just like when pronouncing [t] or [d]. 
• Before palato-alveolars and palatals, the nasal is palatalised [n^j]; ancho (wide), cónyuge (spouse). Note that it is not identical to the platal nasal ñ. (On the Sounds of Speechsite, this nasal is represented as [ň]). 
• Before velars, we pronounce a velar nasal; [ŋ] – manga (sleeve), ángel (angel).

Preconsonantal nasal allophones.
Source: Sounds of Speech
https://soundsofspeech.uiowa.edu/main/spanish