Read Romans 12:6 Using Other Translations
Having then gifts differing according to the grace that is given to us, whether prophecy, let us prophesy according to the proportion of faith;
Having gifts that differ according to the grace given to us, let us use them: if prophecy, in proportion to our faith;
In his grace, God has given us different gifts for doing certain things well. So if God has given you the ability to prophesy, speak out with as much faith as God has given you.