Looks like a lemon to me. No scale on the pictures but they look too big for Mexican limes. Yellow limes are overripe and drop off the tree soon after turning yellow so it would be unlikely to find a tree with just yellow limes and none on the ground.
Identification may have been confused in the translation since the Mexican names for the two fruits are almost exchanged with the English words. Lima is a Mexican Lemon and Limon is a Mexican Lime. Perhaps the label said "Mexican Lima" - with an "a" at the end.
Here is a picture of my Mexican Limes. The close-up shot distorts the image a little so the fruit appears a bit larger than they should relative to the scale. The larger green and yellow limes are about 1.25" long. The green one is the one to eat and has greenish juice. The yellow ones are slightly sweeter but have a slightly unpleasant bitter aftertaste. The juice looks brown. I've also included a leaf. My Mexican friends can identify citrus trees just by looking at the leaves. The big distinction, other than size is the web along the leaf stem. On some citrus it is almost like a second leaf. On the lime it is barely noticeable and on my lemon it isn't there at all.
