linear regression without intercept with dummy variables

#1
Hello, i run simple linear with one dummy variables and no intercept.
i would like to understand the meaning of this.
for example, my beta1=1.2, then if my dummy variable equal one, then y=1.2, but if my dummy variable equal zero, then y=0 ??? i know it's not right, what i should do?
i know that my intercept should be zero.
thank you