That x is probably representing an interaction term.
You should really give us more information about the data (and the experiment which produced it), but the SS's here seems to be sequential SS's, as $0.668+0.357+1.078
=2.103$. Note also that for the df's (degrees of freedom) from the table we have: $119-78-2-39=0$, so there is no df's left for error. That means that the interaction term
Item × Subjects here is confounded with Error.
The anova table shows that indeed the interaction is used as an estimate of error variance, since $ 0.178/0.014 = 12.71429$ and
pf(12.71429, 2, 78, lower.tail=FALSE) returns
1.662293e-05. How can it be allowable to use an interaction as error? Again, it would help to know the specifics of this experiment, but: Assuming this is a randomized experiment, with some
Subjects randomized to some treatment group
Item. Then the interest is really in comparing the different treatments. The
Subjects are just some random persons/animals/whatever used to compare the
Items. We are not specifically interested in comparing different
The act of randomization means that there should not be systematic differences between the subjects randomized to the different treatments, the subjects are in reality a random factor. The act of randomization is what justifies the use of the interaction as error.