Well, I'm learning English, (I speak Spanish) sometimes I use the translator or the dictionary and several times I find this sign in the phonetic transcription, what am I supposed to do?
IPA doesn't use the macron below
◌̱. The minus sign below
◌̠ looks basically the same and can be used to indicate a retracted articulation; but this is not necessary in English dictionaries.
That means the phonetic transcription of your dictionary or website is probably not IPA. You will find a description of its symbols or ‘phonetic key’ in the introduction, or the 'about' page or similar.
It's impossible to answer the question without knowing which dictionaries are you looking at. But what some dictionaries do is to use a macron below / underlining to indicate the stressed syllable. This in IPA is indicated instead by the
ˈ symbol before the syllables. That is, some dictionaries will show 'access' as
æ̱kses rather than IPA
/ˈæksɛs/. Sometimes a dot below
◌̣ is used for short stressed vowels, and underlining for long stressed.