I need help

You can do either in DAX or power query. I prefer Power Query.

DAX, you can do with "Switch" and "Contains", "ContainsString"

• https://dax.guide/containsstring/ 
• https://dax.guide/containsstringexact/
• https://dax.guide/contains/ 
• https://dax.guide/switch/

DAX - Add new Column:

Product Type Column = 

var _pt_1stChar = LEFT('Table'[Variety Code], 1)

RETURN SWITCH(
  TRUE(),
  _pt_1stChar = "C", "Meat",
  _pt_1stChar = "P", "Fish",
  _pt_1stChar = "F", "Fruits & Vegetables"
)

DAX - Add new measure:

Product Type Measure = 
var _pt_1stChar = LEFT(SELECTEDVALUE('Table'[Variety Code]), 1)

RETURN SWITCH(
  TRUE(),
  _pt_1stChar = "C", "Meat",
  _pt_1stChar = "P", "Fish",
  _pt_1stChar = "F", "Fruits & Vegetables"
)

Power query, you can do with "Text.StartsWith" or "Text.Contains" per your needs and Conditional column:

• https://docs.microsoft.com/en-us/powerquery-m/text-startswith
• https://exceltown.com/en/tutorials/power-bi/power-query-get-and-transform/conditional-column-in-power-query-and-in-power-pivot-queries/ 
• https://www.mssqltips.com/sqlservertip/6362/conditional-column-in-power-bi/ 
• https://radacad.com/conditional-column-in-power-bi-using-power-query-you-can-do-anything

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45Wck4EA6VYnWilZAQzIB9JvCAfwXYrggEwN62oCEkgFgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Variety Code" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Variety Code", type text}}),
    #"Added Conditional Column" = Table.AddColumn(#"Changed Type", "Product Type", 
    
    each if Text.StartsWith([Variety Code], "C", Comparer.OrdinalIgnoreCase) then "Meat" 
    else if Text.StartsWith([Variety Code], "P", Comparer.OrdinalIgnoreCase) then "Fish" 
    else if Text.StartsWith([Variety Code], "F", Comparer.OrdinalIgnoreCase) then "Fruits & Vegetables" else null)
 
in
    #"Added Conditional Column"

I dont know spanish, sorry, I used some text for Variety code to get the code for you.