Mezaylem kellem diun filyad zôddlem literally means that one won a god-daughter by giving away a banana from the table, that is, belonging to somebody else. It is a reference to a favour one does, and takes credit for, without having to pay for it oneself, for instance by giving a gift that either belongs to somebody else or is ‘on the house’. Like many other proverbs of this type, it is an observational proverb that isn’t meant to impart wisdom as much as it tries to portray a particular situation with some insight into it.
The word mezaylem is a contraction of mezavelem, literally meaning “from on the table” (locative on). If it were instead in a container, e.g., in a jar, we would use the locative in, e.g., bhornêntlem, meaning ‘from inside a/the jar’. As you can see, it isn’t a simple locative but a compound postposition, corresponding to a compound preposition in English: from on or from inside. A simple locative would be mezar (on a/the table) or bhornênt (in a/the jar).
Diun literally means ‘having given’ or, as is the case here, ‘by giving’.
The word filyad comes from the Portuguese afilhado or afilhada, i.e., godson or god-daughter respectively, so filyad or filhad can be any of the three genders — neuter if it refers to a young girl, as is the case here. Notice that the neuter is apparent here only because the sentence is in the past definite. And, as has been mentioned elsewhere in Nostalgoa, when a transitive verb like diunk (to give) is used in the past definite, the verb abandons its loyalty to the subject and agrees with the object (filyad), which is how we come to know that it is neuter (i. e., a young girl), because zôddlem is neuter. Had the sentence been in the present, i.e., with “zôddta” instead of “zôddlem“, the gender of filyad would be unknown.
Yet another observation. Notice that the sentence is devoid of a subject. It has a verb (zôddlem) and an object (filyad), but no subject. Such a thing is very conveniently done when it is the verb that is important, and not the subject, that is, when the focus is on what is done, rather than on who does it.