@Dakila
Good for you to notice that.
It has to do with the use of the word “wala” in the sentence.
There are two Filipino words that alter the nature of an object-focus verb. These are “wala” and “mayroon/meron”. There are three words if we’ll include “may”, which gives the same meaning as “mayroon”. “May” and “mayroon” though are not directly interchangeable.
“Mayroon/Meron” (there + "to be") and “wala” (there + "to be" + none) have their own rules on usage.
1. When they are used as modifiers of nouns or verbs, they are followed by the “na” linker. That’s why you will often see them as “mayroong/merong” and “walang” because “mayroon na” = “mayroong” and “wala na” = “walang”.
Mayroon. = There is/are/was/etc..
Wala. = (There is/are/was/etc.) None.
Mayroong/May tao sa kuwarto. = There is a person in the room.
Walang tao sa kuwarto. = There is no person in the room.
Mayroong/May natutulog. = There is someone sleeping.
Walang natutulog. = There is no one sleeping.
2. When they are used with actor/subject-focus verbs, THEY REPLACE THE ACTOR/SUBJECT.
Kumain SI John NG tinapay. = John ate bread.
Kumain SIYA NG tinapay. = He ate bread.
Mayroong/May kumain NG tinapay. = There was someone who ate bread/the bread.
Walang kumain NG tinapay. = There was no one who ate bread/the bread.
3. When they are used with object-focus verbs:
A. THEY REPLACE THE OBJECT AND THE ACTOR BECOMES THE SUBJECT. As the subject, the use of “si” and “ang” would then apply.
Bin
asa NI John ANG libr
ó. = ANG libro ay binasa NI John. = John read the book.
Mayroong/May bin
asa SI John. = SI John ay mayroong/may binasa. = John read something.
Walang bin
asa SI John. = SI John ay walang binasa. = John read nothing.
Kin
ain NG pusa ANG tinapay. = ANG tinapay ay kinain NG pusa. = The cat ate the bread.
Mayroong kinain ANG pusa. = ANG PUSA ay mayroong/may kinain. = The cat ate something.
Walang kinain ANG pusa. = ANG pusa ay walang kinain. = The cat ate nothing.
B. if the actor is represented by a pronoun (which would normally be in THE POSSESSIVE FORM – ko, mo, niya, etc.), it CHANGES TO THE FORM OF A SUBJECT PRONOUN (ako, ka (ikaw), siya, etc.) and immediately follows it. The linker “na” then gets attached to the pronoun instead. (This rule applies to your question.)
Bin
asa NIYA ANG libr
ó. = ANG libro ay binasa NIYA. = He read the book.
Mayroon SIYANG binasa. = SIYA ay mayroong/may binasa. = He read something.
Wala SIYANG binasa. = SIYA ay walang binasa. = He read nothing. (This applies to your question.)
Kin
ain NIYA ANG tinapay. = He ate the bread.
Mayroon SIYANG kinain. = SIYA ay mayroong/may kinain. = He/It ate something.
Wala SIYANG kinain. = SIYA ay walang kinain. = He ate nothing.
Applying the above:
Walang sinabi SI Mary sa akin. = SI Mary ay walang sinabi sa akin. = Mary did not say anything to me/Mary said nothing to me.
Wala SIYANG sinabi sa akin. = SIYA ay walang sinabi sa akin. = She did not say anything to me/She said nothing to me. (This was my example.)