Throughout the Bikini Bottom hub world, there are hidden spatulas. You need at least 40 spatulas to obtain them all as they are throughout the different sections. However, you can get some here and there as you complete the game.
Those locations are:
1.) On top of Spongebob's house by activating the buttons and jumping house to house
2.) Annoying Squidward in his house by jumping repeatedly in front of him (Literally annoying him)
3.) Sandy's Treedome, in which you have to defeat all of the robots to achieve it
4.) The top of shady shoals, which you reach by going on top of the police station using the bowling button next to it and jumping platform to platform.
5.) The Krusty Krab, which is obtained the same as Sandy's Treedome.
6.) The top of the Chum bucket, which you use your cruise missile to press the buttons on the side of it and jump up using the trampoline.
7.) Inside the Chum Bucket hidden behind the ventilation on the left of the kitchen door
I suggest not worrying about it until you unlock the 3rd section of Bikini Bottom.