This is the 132nd most frequent Hebrew word.
בלבד
"Only" or "just."
Here, 'בלבד' highlights exclusivity, emphasizing the choice of tea to the exclusion of any other options.
אני רוצה רק תה בלבד.
I only want tea, exclusively.
In this usage, 'בלבד' is used to denote that the offer is specifically limited to Mondays, excluding other days.
ההצעה תקפה לימים שני בלבד.
The offer is valid for Mondays only.
'בלבד' here specifies a limiting condition, making the statement apply exclusively to children under 12.