This look is a mix of shooting style and editing.

For the soft background, the main factor is shallow depth of field: use a wide aperture, typically with a fast prime lens, and keep the subject separated from the background. Diffuse lighting also helps the image feel soft because it avoids harsh shadows.

For the blue/turquoise color, in Photoshop you can start by:

• lowering overall saturation a bit
• brightening midtones with curves or levels
• using a gradient map or other color-toning adjustment to add cool tones
• masking so the effect is stronger in the background and lighter on skin tones
• applying edits on separate layers and reducing opacity to fine-tune the look

You can also create a similar effect in-camera. One method is to gel your flash with an orange gel, light the subject mostly with flash, leave the background lit more by ambient light, then adjust white balance for the gel when processing RAW. That can make the background shift blue while keeping the subject natural.

So: shallow DOF + soft light for the softness, then selective cool toning and brightness adjustments for the color style.