À

This letter represents the sound /æ/ as in cat, fat, hat, sat.
It serves to show where /æ/ is stressed in typically irregular circumstances.

E.g.
analysis -> anàlysiʃ /əˈnælɪsəs/
combatant -> combàtant /kəmˈbætnt/
alfalfa -> alfàlfa /ælˈfælfə/

Some words use it for etymological or grammatical reasons

alphabet -> àlfabet /ˈælfəˌbɛt/
Because e would typically suggest stress on the vowel before it, à is used.

admiral -> àmiral /'æmərəl/
Because etymologists of yesterday have confused the origin of this Arabic word with Latin, 
I've removed the unetymological -d-, but have added the accent to indicate where its stress lies without question.

https://www.etymonline.com/word/admiral#etymonline_v_5128