Answer:
promotional signage
Step-by-step explanation:
Base on the the scenario been described in the question, where Manila display large signs in the store window to attract customers and she also puts up placards to display the reduced prices for all the items for her costumers we can say that she uses what is know as promotional signage
Promotional signage is a form design or use of signs and different kinds of symbols to inform or pass message to a specific group costumers, usually the main of this is to markets your products as seen in the case where Manila where she put placards indicating reduced price on the items she sells.