Explain the metaphors and similes.

Pablo Neruda's "Ode to My Socks" is full of figurative language, including similes and metaphors. Similes are figurative comparisons using "like" or "as." Metaphors are implicit figurative comparisons, as we will see in examples from the poem. 
Neruda's speaker is writing about a pair of socks sewn for him by Maru Mori, as mentioned in line 1. Neruda describes both the socks and his feet (wearing the socks) with similes and metaphors.
First, the speaker describes "two socks as soft / as rabbits" (lines 6-7). Obviously, the speaker is commenting on the soft texture of the socks at this point. When he puts the socks on his feet, the speaker says that he does so "as though into / two / cases / knitted/ with threads of / twilight" (10-15). This is another simile, and this one seems to give the socks a glittering or spectacular quality. The socks then transform the speaker's feet. In a series of metaphors, the speaker writes: 

my feet weretwo fish madeof wool,two long sharkssea-blue, shotthroughby one golden thread,two immense blackbirds,two cannons: (18-26)

A couple of these metaphors are relatively understated: the speaker likens his feet to "fish" and "blackbirds," though the birds are described as "immense." The other two are more "violent," a word the speaker uses to describe the socks in line 16: he likens his feet to "sharks" and "cannons." This underscores the power and the imposing nature of his feet when they are in these special socks.
The speaker then goes on to explain that he feels his feet are unworthy of these magnificent socks. He writes, 

They wereso handsomefor the first timemy feet seemed to meunacceptablelike two decrepitfiremen, firemenunworthyof that wovenfire,of those glowingsocks. (36-47)

In an extended simile, the speaker compares his feet to "decrepit firemen" who are "unworthy" of fighting the "fire" lit by these socks. The socks themselves have a "glowing" appearance, a brilliance, and the speaker feels that his ordinary feet are no match for these glorious socks.
In another shift, the speaker says that despite his feelings of unworthiness, he decides not to hide the socks away: 

as schoolboyskeepfireflies,as learned mencollectsacred texts (52-57). 

These similes indicate that he will not keep them merely to look at and admire. He will not put them somewhere special simply to look at them. The speaker continues to say that he will not keep them in a metaphorical "golden / cage" (61-62). He will not feed them metaphorical "birdseed" and "melon" (64-65). He will not keep them locked up. Instead, the speaker decides to put on the socks:

Like explorersin the jungle who handover the very raregreen deerto the spitand eat itwith remorse,I stretched outmy feetand pulled onthe magnificentsocksand then my shoes. (66-78). 

Here, the speaker uses an extended simile compare himself to "explorers" who kill and eat a "very rare / green deer." They know they are transgressing in some way, but they also feel like they must put the deer to good use. The speaker similarly feels unworthy of his socks, but he puts them on anyway. 
Throughout the poem, the speaker's use of simile and metaphor express the wonder he feels at these socks and his inability to measure up to the brilliance of them; however, he ultimately decides to embrace and appreciate the socks by wearing them.