p value in R - beginners question

8.15*10^-1

Dear all,

i have done some regression analyses but i do not understand the p value. 
These are the results

                                       t-value  p value
geno.1           -0.229 0.978 -0.234 8.15e-01
geno.5            0.647 1.146  0.565 5.73e-01
stress:geno.5    -1.337 1.022 -1.307 1.92e-01

how can i see if my results are significant ? (apart from looking at the
t-value). Can someone explain the p values?

thanks

niki