Pregnant 6 months and doctor told me there's spot in baby's heart, what's that?

A lot of things: Heart 'spots' can be any number of 'issues', so please ask the doctor who did the ultrasoundr the question you just asked me.

Echogenic focus/: Can be entirely normal. Your doctor may suggest additional testing to assure that that is the case.

See below: It is a non-specific term reflecting an area of the heart that might have increased minieralization, and so show up more on an echo. Can be found in normal hearts at a rate of about 3%. There may be some association with genetic abnormalities, but it is called a "soft finding" that is to say inconclusive.