Ship helipad markings

They obviously mark the helicopter landing area, but more specifically, act as lineup and hover cues for specific iterations aboard. Lineup cues for landing approach, touchdown, where nose and main wheels go for specific helos (on LHA/LPH/LHD ships), hover position for VERTREP or vertical replenishment operations, hover position for HIFR or Helicopter Inflight Refueling ops (and sometimes HIFR positional awareness lighting), etc. Also within the markings will be embedded deck edge lighting, lineup lighting, and obstruction lighting, located along with other flight deck lights such as deck status lights and waveoff lights. Some ships, you make a straight-in approach, others you make an oblique approach, and they are marked appropriately for that.
 
I'll just amplify MikeD's post above if you'd like.

In the specific image you are referencing, that area is actually used for multiple purposes: Launch/recovery, HIFR (helicopter inflight refueling), and VERTREP (vertical replenishment). So for each purpose, the markings overlap each other.

Deck edge marking - the rough square-shape box along the edges of the flight deck that define the entire landing area.

For launch/recovery, there are two kinds of operations, free deck (pilot just lands on the deck) and RAST (Recovery, Assist, Securing, and Traversing) (pilot either lands in or gets hauled down onto the ship into the RAST or what we just call the beartrap.)

Landing lineup line - there are two: one that is parallel to the ship's centerline and one that is diagonal across the landing area. Helicopters line up on this line to land. I believe on this particular class ship (DDG-51) the diagonal line is the primary lineup line used for free deck landings. The straight one is used only by the H-60.
Landing circle - ensures obstruction clearance when the helicopter lands with the nose wheel (or main gear for tailwheel helos) within the forward half of the circle. In this image the landing circle is centered on the intersection of the two lineup lines. In the center of the landing circle, there is a touchdown spot.
The square inside the landing circle is where the right main gear for an H-60 is supposed to go if it's landing on the straight lineup line. There is a corresponding square that is hidden underneath the helicopter for the left main gear.

There are two hash marks on the left and right edge of the flight deck used for RAST operations. The forward hash marks are the RAST hover reference line. The aft hash marks are the aft limit reference line - with the hash mark indicating aft limit of the main landing gear for the H-60 helicopter.

The H on the aft end of the flight deck on the port side indicates the HIFR hovering area. The helo hovers here to pick up the fueling rig from the ship with its hoist. After the fueling rig is connected to the helo, the helo then offsets to port and flies formation with the ship to refuel. When it's done refueling, it moves back over the H and hoists the fueling rig back onto the ship.

For VERTREP, there are two lines of "T"s. There is a VERTREP T line which is the forward line consisting of Ts and a VERTREP ball T line which is the after line consisting of alternating balls and Ts.
The lines indicate the forward limit for the rotor hub to ensure obstruction clearance for the rotor with the ship's superstructure. The ball T line is the forward limit for H-3/-53/-60 helicopters, and the T line is for H-46 helicopters.

Anyways I've run out of markings to type about - probably more info than you care to know.
 
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